Stabilization of acid catalysts

ABSTRACT

The invention is directed to a method of stabilizing metalloaluminophosphate molecular sieves and catalysts derived therefrom. In particular, the invention is directed to a method of treating such molecular sieves with chemisorbed ammonia, which may be easily desorbed before or during use and after storage. The invention is also directed to formulating the molecular sieve into a catalyst useful in a process for producing olefin(s), preferably ethylene and/or propylene, from a feedstock, preferably an oxygenate containing feedstock.

FIELD OF INVENTION

This invention relates to a method of stabilizingmetalloaluminophosphate molecular sieves during storage and handling, tostabilized metalloaluminophosphate molecular sieves andmetalloaluminophosphate molecular sieve containing catalysts and totheir use in adsorption and conversion processes, especially theconversion of oxygenates to olefins.

BACKGROUND OF THE INVENTION

Olefins are traditionally produced from petroleum feedstock by catalyticor steam cracking processes. These cracking processes, especially steamcracking, produce light olefin(s) such as ethylene and/or propylene froma variety of hydrocarbon feedstock. It has been known for some time thatoxygenates, especially alcohols, are convertible into light olefin(s).Methanol, the preferred alcohol for light olefin production, istypically synthesized from the catalytic reaction of hydrogen, carbonmonoxide and/or carbon dioxide in a methanol reactor in the presence ofa heterogeneous catalyst. The preferred methanol conversion process isgenerally referred to as a methanol-to-olefin(s) process, where methanolis converted to primarily ethylene and/or propylene in the presence of amolecular sieve.

Some of the most useful molecular sieves for converting methanol toolefin(s) are the metalloaluminophosphates such as the aluminophosphates(ALPO's) and the silicoaluminophosphates (SAPO's). SAPO synthesis isdescribed in U.S. Pat. No. 4,440,871, which is herein fully incorporatedby reference. SAPO is generally synthesized by the hydrothermalcrystallization of a reaction mixture of silicon-, aluminium- andphosphorus-sources and at least one templating agent. Synthesis of aSAPO molecular sieve, its formulation into a SAPO catalyst, and its usein converting a hydrocarbon feedstock into olefin(s), particularly wherethe feedstock is methanol, is shown in U.S. Pat. Nos. 4,499,327,4,677,242, 4,677,243, 4,873,390, 5,095,163, 5,714,662 and 6,166,282, allof which are herein fully incorporated by reference.

It has been discovered that metalloaluminophosphate molecular sievessuch as aluminophosphate (ALPO) and especially silicoaluminophosphate(SAPO) molecular sieves, are relatively unstable to moisture containingatmospheres such as ambient air when in the calcined or partiallycalcined state; this state is sometimes referred to as the activatedstate. It has also been observed that the relative stability is in partrelated to the nature of the organic templating agent used in themanufacture of the SAPO molecular sieve. Briend et al., J. Phys. Chem.1995, 99, 8270-8276, teaches that SAPO-34 loses its crystallinity whenthe template has been removed from the sieve and the de-templated,activated sieve has been exposed to air. Data is presented, however,which suggest that over at least the short term, crystallinity loss isreversible. Even over a period of a couple years, the data suggest thatcrystallinity loss is reversible when certain templates are used.

U.S. Pat. No. 4,681,864 to Edwards et al. discusses the use of SAPO-37molecular sieve as a commercial cracking catalyst. It is disclosed thatactivated SAPO-37 molecular sieve has poor stability. However, stabilitycan be improved by using a particular activation process. According tothe process, retained organic template present from the synthesis of theSAPO-37 is removed from the core structure of the sieve just prior tocontacting with feed to be cracked. The process calls for subjecting thesieve to a temperature of 400-800° C. within the catalytic crackingunit.

U.S. Pat. No. 5,185,310 to Degnan et al. discloses another method ofactivating silicoaluminophosphate molecular sieve compositions. Themethod calls for contacting a crystalline silicoaluminophosphate withgel alumina and water, and thereafter heating the mixture to at least425° C. The heating process is first carried out in the presence of anoxygen-depleted gas, and then in the presence of an oxidizing gas. Theobjective of the heating process is to enhance the acid activity of thecatalyst. The acid activity is enhanced as a result of the intimatecontact between the alumina and the molecular sieve.

U.S. Pat. No. 6,051,746 to Sun et.al. discloses a process for theconversion of oxygenated organic materials to olefins using a modifiedsmall pore molecular sieve catalyst. The molecular sieve catalyst ismodified with polynuclear aromatic heterocyclic compounds in which atleast three interconnected ring structures are present having at leastone nitrogen atom as a ring substituent, and with each ring having atleast five ring members.

European Published Application EP-A2-0,203,005 discusses the use ofSAPO-37 molecular sieve in a zeolite catalyst composite as a commercialcracking catalyst. According to the document, if organic template isretained in the SAPO-37 molecular sieve until a catalyst compositecontaining zeolite and the SAPO-37 molecular sieve is activated duringuse, and if thereafter the catalyst is maintained under conditionswherein exposure to moisture is minimized, the crystalline structure ofthe SAPO-37 zeolite composite remains stable.

PCT Publication No. WO 00/74848 to Janssen et al. describes a method ofprotecting the catalytic activity of silicoaluminophosphate molecularsieves by covering the catalytic sites with a shield prior to contactingwith an oxygenate feedstock. The shielding may be achieved by retainingtemplate within the pores of the molecular sieve, by using carbonaceousmaterials, or by using an anhydrous gas or liquid environment.

PCT Publication No. WO 00/75072 to Fung et.al. discloses a method foraddressing the problems relating to protecting molecular sieves fromdamage due to contact with moisture and damage due to physical contact.The method requires the heat treatment of a molecular sieve containing atemplate under conditions effective to remove a portion of the templatefrom the microporous structure and cooling the heated molecular sieve toleave an amount of template or degradation product thereof effective tocover catalytic sites within the microporous structure.

PCT Publication No. WO 00/74846 to Janssen et.al. discloses a method forpreserving the catalytic activity of silicoaluminophosphate molecularsieves which comprises heating of template-containingsilicoaluminophosphate in an oxygen depleted environment underconditions effective to provide an integrated catalyst life which isgreater than that obtained using a non-oxygen depleted environment.

U.S. Pat. No. 6,051,745 to Wu et.al. is concerned with overcoming theproblem of the excessive production of coke, which occurs when somesilicoaluminophosphates are used as catalysts in the conversion ofoxygenated hydrocarbons to olefins. The solution proposed is the use ofnitrided silicoaluminophosphates. Nitridation is achieved by thereaction of the silicoaluminophosphate with ammonia at elevatedtemperatures, typically in excess of 700 ° C. The nitridation reactionis essentially irreversible and destroys irreversibly the acidic sitesof the molecular sieve, as the acidic OH groups are converted to NH₂groups during the nitridation process.

U.S. Pat. No. 4,861,938 to Lewis et.al describes a process forconverting feedstocks. Matrix material used in the manufacture of thecatalyst for the process may be conditioned prior to catalystmanufacture by exposure to ammonia.

U.S. Pat. No. 5,248,647 to Barger describes a process for thehydrothermal treatment of silicoaluminophosphate molecular sieves. Theprocess requires the treatment to be undertaken at temperatures inexcess of 700° C. to destroy a large proportion of the acid sites whilstat the same time retaining a significant proportion of the originalcrystallinity. Also disclosed in this document is a test method fordetermining the molecular sieve acidity. This test method requires theadsorption of ammonia onto the molecular sieve, followed by desorptionwithin the temperature range of 300 to 600° C. and titration of thedesorbed ammonia

As seen from the disclosures described herein, manymetalloaluminophosphate molecular sieves will exhibit a shortenedcatalytic life when exposed to a moisture-containing environment. Thisloss of catalytic life is, in some instances, irreversible, and canoccur over a very short period of time. In essence, this loss ofcatalytic life is due to a loss in the number of acid catalytic sites.In addition there may be irreversible loss of molecular sievecrystallinity and porosity on ageing during storage and handling aftermanufacture.

It is desirable therefore to develop methods for the treatment ofmetalloaluminophosphate molecular sieves and catalysts containing thesemolecular sieves, which ensure that the catalytic properties andphysical properties of these materials, such as porosity andcrystallinity, are retained after storage and handling.

SUMMARY OF THE INVENTION

The present invention provides a method for the preparation ofstabilized metalloaluminophosphate molecular sieves andmetalloaluminophosphate molecular sieve containing catalysts, and totheir use in adsorption and conversion processes, especially theconversion of oxygenates to olefins, particularly light olefin(s). Inthe context of the present invention reference will be made throughoutthis specification to metalloaluminophosphate molecular sieves; thisterm as used in this specification encompasses aluminophosphate (ALPO)and silicoaltiminophosphate (SAPO) molecular sieves and derivatives ofthese molecular sieves as hereinbefore and hereinafter described.

In one embodiment the invention is directed to a method of providing astabilized metalloaluminophosphate molecular sieve, which methodcomprises the steps of

-   -   a. providing a metalloaluminophosphate molecular sieve having a        framework structure,    -   b. treating the metalloaluminophosphate molecular sieve with a        source of ammonia under conditions to chemisorb ammonia with the        metalloaluminophosphate molecular sieve, and    -   c. maintaining the ammonia chemisorbed with the        metalloaluminophosphate molecular sieve for a period of at least        24 hours.

In another embodiment the invention is directed to a method of providingan active metalloaluminophosphate molecular sieve, which methodcomprises the steps of

-   -   a. providing a metalloaluminophosphate molecular sieve having a        framework structure,    -   b. treating the metalloaluminophosphate molecular sieve with a        source of ammonia under conditions to chemisorb ammonia with the        metalloaluminophosphate molecular sieve,    -   c. maintaining the ammonia chemisorbed with the        metalloaluminophosphate molecular sieve for a period of at least        24 hours, and    -   d. desorbing the chemisorbed ammonia.

In another embodiment the present invention provides a method for themanufacture of a catalyst composition, which method comprises the stepsof

-   -   a. forming a mixture comprising at least one        metalloaluminophosphate molecular sieve having a framework        structure with at least one binder material and/or at least        another catalytically active material, and    -   b. treating the mixture with a source of ammonia under        conditions to chemisorb ammonia with the metalloaluminophosphate        molecular sieve.

In yet a further embodiment the present invention provides a method forthe manufacture of a catalyst composition, which method comprises,forming a mixture comprising at least one metalloaluminophosphatemolecular sieve having ammonia chemisorbed thereon with at least onebinder material and/or at least another catalytically active material,to form a catalyst composition.

In a further embodiment the present invention provides a stabilizedmetalloaluminophosphate molecular sieve, which comprises at least oneaged metalloaluminophosphate molecular sieve and chemisorbed ammonia.

In yet a further embodiment the present invention provides a molecularsieve composition comprising at least one metalloaluminophosphatemolecular sieve in admixture with at least one binder and/or at leastanother catalytically active material and chemisorbed ammonia.

In an additional embodiment the present invention provides a molecularsieve composition comprising at least one metalloaluminophosphatemolecular sieve having ammonia chemisorbed thereon and in admixture withat least one binder and/or at least another catalytically activematerial.

The present invention also provides for the use of ammonia to stabilizea metalloaluminophosphate molecular sieve during storage and/orhandling.

In a further embodiment the present invention provides a method forstoring metalloaluminophosphate molecular sieves which method comprisesmaintaining the metalloaluminophosphate molecular sieve in contact withammonia in a chemisorbed state during storage.

The metalloaluminophosphate molecular sieves and compositions comprisingthese molecular sieves as made by or described in the above embodimentsand in the detailed description of the present invention find utility inabsorption processes and in hydrocarbon conversion processes.

Accordingly the present invention also provides for a hydrocarbonconversion process comprising the steps of:

-   -   a) introducing a feedstock to a reactor system in the presence        of a metalloaluminophosphate molecular sieve as prepared or        described in any one of the embodiments of the present        invention;    -   b) withdrawing from the reactor system an effluent stream; and    -   c) passing the effluent gas through a recovery system recovering        at least one or more conversion products.

In this embodiment, the invention is preferably directed to a processfor producing olefin(s) or alkyl amines in the presence of any of themetalloaluminophosphate molecular sieves and catalyst compositions ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood by reference to theDetailed Description of the Invention when taken together with theattached drawings wherein:

FIG. 1 shows a dynamic gas-volumetric adsorption apparatus suitable fortreatment of metalloaluminophosphate molecular sieves with ammonia;

FIG. 2 shows the methanol adsorption capacity of a SAPO-34 molecularsieve after different NH₃-treatments as a function of the ageing time;

FIG. 3 shows the methanol conversion of a SAPO-34 molecular sieve aftervarious periods of ageing;

FIG. 4 shows the methanol conversion of an NH₃ treated SAPO-34 molecularsieve after various periods of ageing;

FIG. 5 shows the effect of ageing, with and without NH₃ treatment, onthe XRD pattern of a SAPO-34 molecular sieve; and

FIG. 6 shows DRIFTS Infrared spectra illustrating protection andregeneration of acidity during and after ageing of a SAPO-34 treatedwith NH₃.

DETAILED DESCRIPTION OF THE INVENTION

Introduction

The invention is primarily directed toward a method of stabilizingmetalloaluminophosphate molecular sieves. It has been found that thetreatment of metalloaluminophosphate molecular sieves with ammonia sothat the ammonia is chemisorbed results in stabilizedmetalloaluminophosphates that are resistant to degradation duringexposure to moisture. Through this method, treatedmetalloaluminophosphate molecular sieve materials and catalystcompositions are provided which retain most if not all of their originaladsorption, catalytic and/or physical properties on storage even afterextensive periods of exposure to ambient atmosphere or steam. Withoutbeing bound to any particular theory, it is believed that the ammoniareacts in a reversible way with the Broensted acid sites within themetalloaluminophosphate molecular sieve and in doing so protects themfrom attack by moisture during storage and handling.

Chemisorption of Ammonia

A key aspect of the present invention is the chemisorption of ammoniawith acid catalytic cites of the metalloaluminophosphate molecularsieve. As indicated above it is known in the art to treat such molecularsieves with ammonia under nitridation conditions. Nitridation results inan irreversible chemical reaction between acid sites of the molecularsieve and ammonia or other nitrogen sources. The nitridation reaction isessentially irreversible and destroys irreversibly the acidic sites ofthe molecular sieve, as the acidic OH groups are converted to NH₂ groupsduring the nitridation process. This is in contrast with the process ofchemisorption according to the present invention, which is a chemicaladsorption process in which a weak chemical bond is formed betweenmolecules in the gaseous or liquid state and a solid surface. Due tothis weak bonding the process is reversible upon the application ofheat. In the context of the present invention ammonia is the molecule,which is in either the gaseous or liquid state, and the solid surface isthe metalloaluminophosphate molecular sieve.

Chemisorption Process

Preferably prior to chemisorption of the ammonia themetalloaluminophosphate molecular sieve is activated. The primaryfunction of the activation process is to remove volatile compounds andtemplate utilized in the synthesis of the molecular sieve that may stillbe present in or on the molecular sieve. It is envisaged that in theprocess of the present invention the molecular sieve may be partiallyactivated. By partially activated is meant that a proportion of thetemplate or by-products of the template is not removed prior tochemisorption. It is preferred that substantially all the template beremoved. Activation is achieved using conventional calcinationtechniques and conditions as discussed below. Typical calcinationtemperatures are in the range from about 400° C. to about 1,000° C.,preferably from about 500° C. to about 800° C., and most preferably fromabout 550° C. to about 700° C., preferably in a calcination environmentsuch as air, nitrogen, helium, flue gas (combustion product lean inoxygen), or any combination thereof.

The activated molecular sieve may be chemisorbed with ammonia under avariety of conditions. These conditions are selected to ensure thatammonia is chemisorbed with at least the Broensted acid sites of themolecular sieve. The ammonia is chemisorbed in the liquid or gaseousstate. Preferably it is chemisorbed in the gaseous state. In oneembodiment the activated molecular sieve is introduced into a treatmentvessel, which enables the molecular sieve to be degassed. This istypically achieved by utilizing a vacuum, preferably with theapplication of heat. Typically the molecular sieve may be degassed undervacuum at a temperature within the range of 10 to 600° C., andpreferably 20 to 300C. In an alternative embodiment the molecular sieveis treated as activated without degassing.

The ammonia may be introduced to the treatment vessel containing thedegassed molecular sieve or the as activated molecular sieve. Theammonia may be introduced with or without the use of an inert carriergas such as dry nitrogen or similar gas. When used in a gaseous mixturethe partial pressure of ammonia in the mixture is not critical.Preferably, the ammonia is present in excess of that required to reactwith at least the Broensted acid sites within the molecular sieve. Theammonia may be introduced at ambient temperatures or at elevatedtemperatures. It is important that the temperature is selected so thatthe ammonia does not react with the molecular sieve under nitridationconditions. It is possible to determine suitable temperatures for anygiven molecular sieve by observing the chemisorption and desorption ofammonia using analytical techniques such as the Infrared techniquesdescribed herein. If a temperature is used that results in anirreversible reaction with the ammonia as may be determined by thesetechniques, then a lower reaction temperature should be selected. Theammonia may be reacted with the molecular sieve at a temperature of lessthan 500° C., ideally less than 450° C., preferably less than 300° C.;ideally within the temperature range of 0 to 500° C. or 10 to 450° C.,preferably 20 to 300° C., or 20 to 450° C., and most preferably 100 to250° C. It has been found to be particularly effective if thechemisorption reaction is undertaken at temperatures preferably inexcess of 100° C., more preferably in excess of 150° C., and mostpreferably in excess of 200° C. The ammonia may initially be introducedat a low temperature e.g. less than 100° C. and the temperature may thenbe raised above this temperature during the reaction. The exact timerequired to complete the chemisorption process is dependent on theamount of acidity present in the molecular sieve. The amount of aciditymay be determined by test methods known in the art such as ammonia TPD.The time for chemisorption and/or the amount of ammonia used and/or thetemperature of chemisorption may be used to ensure that sufficientammonia is chemisorbed. It is also possible to determine the optimumconditions for any given molecular sieve by undertaking a series ofadsorption and desorption experiments to determine under what conditionscomplete chemisorption is achieved. Once determined these conditions maybe used in the chemisorption process. In this regard the ammonia TPDtest method and Infrared spectroscopy may be used. Typically, whengaseous ammonia is used and the chemisorption is undertaken on adegassed sample of molecular sieve, the chemisorption process iscomplete after 30 minutes exposure to ammonia at a temperature in excessof 100° C. At temperatures in excess of 100° C. it is the Broensted acidsites, which are substantially, chemisorbed with the ammonia; attemperatures below 100° C. other sites including Broensted acid sitesand non-Broensted acid sites may be chemisorbed with the ammonia.

It is envisaged that the chemisorption process with ammonia may beundertaken on a composition comprising metalloaluminophosphate molecularsieve and in particular a catalyst composition. In this embodiment thecomposition comprising metalloaluminophosphate molecular sieve and othermaterials e.g. catalyst componants is exposed to ammonia underconditions that result in the chemisorption of ammonia with themolecular sieve. This exposure to ammonia may be achieved by introducingthe ammonia into the end zone of the calcination unit used in themanufacture of a catalyst composition. This zone is typically attemperatures below the calcination temperature as the catalyst is beingcooled before being introduced into storage drums. In this and otherembodiments the ammonia may be introduced in the presence of an inertgas such as nitrogen.

The molecular sieve comprising chemisorbed ammonia is stable when storedunder ambient conditions. The molecular sieve is also stable in thepresence of water vapour at temperatures of up to 300° C., preferably ofup to 250° C., more preferably of up to 200° C. By stable is meant thatthere is less reduction in the catalytic activity of the chemisorbedmolecular sieve compared to the non-chemisorbed molecular sieve whenstored under or exposed to the same conditions. The molecular sievecomprising chemisorbed ammonia may be maintained in the chemisorbedstate for an extended period of time, which is typically at least 24hours and which may be for any period of storage or handling greaterthan 24 hours. In one embodiment the molecular sieve is maintained inthe chemisorbed state for at least 36 hours, preferably at least 48hours and most preferably at least 72 hours. Ideally it is held in thisstate as long as possible before use. In one embodiment the molecularsieve is held in the chemisorbed state until it is utilized in themanufacture of a catalyst composition. In a further embodiment it isheld in the chemisorbed state prior to introduction as the catalyst orpart of a catalyst composition into a catalyzed reaction. In thisembodiment the preferred catalyzed reaction is a methanol-to-olefinsprocess.

It is also envisaged within the scope of the present invention that thechemisorption process may be undertaken on used metalloaluminophosphatemolecular sieve or used catalyst compositions comprisingmetalloaluminophosphate molecular sieve. During conversion processes,such as methanol-to-olefin processes, it may be necessary to shut thereactor down in either an emergency or in a planned shutdown andmaintenance cycle. When this occurs it is often necessary to remove theused catalyst from the reactor and to place it into temporary storage,which is usually under an inert atmosphere. Sometimes removal is notnecessary or desirable and the catalyst is maintained within the plantitself. In both situations the catalyst is under risk of losing itscatalytic activity and/or other properties due to ageing effects. Inaddition during shut down and start-up the reactor may be underconditions, which generate significant quantities of steam at hightemperature i.e. superheated steam, which is particularly harmful tometalloaluminophosphate molecular sieve containing catalysts. Theammonia chemisorption method of the present invention has been found tobe particularly effective in protecting metalloaluminophosphatemolecular sieve materials against the effects of steam as would bepresent in the methanol-to-olefins process. In this embodiment the usedcatalyst may be treated by ammonia chemisorption as the catalyst isremoved from the methanol-to-olefins plant; the ammonia being desorbedwhen the ammonia chemisorbed catalyst can be re-introduced to the plant.In an alternative embodiment the used catalyst is treated within theplant during or after shutdown. In a particularly preferred embodimentthe used catalyst is exposed to ammonia within the plant at temperaturesabove those at which steam significantly degrades themetalloaluminophosphate molecular sieve. In a methanol-to-olefinsprocess significant steam damage may occur within the temperature rangeof 100 to 350° C. Higher temperatures should be avoided as under theseconditions in the reactor the undesirable nitridation reaction mayoccur.

Desorption Conditions

The metalloaluminophosphate molecular sieve in the ammonia chemisorbedstate may be regenerated by desorption of the ammonia. This may beachieved by heating the ammonia chemisorbed metalloaluminophosphatemolecular sieve at temperatures in excess of 200° C., and preferably inexcess of 400° C., and most preferably in excess of 600° C. Thisdesorption may be achieved using a muffle furnace or similar furnace. Itmay also be achieved by using the same equipment used for calcinationduring manufacture of the molecular sieve or catalyst compositionscontacting the molecular sieve. In one embodiment the ammonia may beremoved during the manufacture of a formulated catalyst under spraydrying conditions. In a further embodiment the ammonia may be removed insitu on introduction of the ammonia chemisorbed metalloaluminophosphatemolecular sieve to a catalytic conversion process such as amethanol-to-olefins process. This may be achieved by introduction ofammonia chemisorbed metalloaluminophosphate molecular sieve to theregeneration unit of the plant.

Aged Molecular Sieve

In the context of the present invention an aged metalloaluminophosphatemolecular sieve is a metalloaluminophosphate molecular sieve assynthesized or formulated as a catalyst, which has been stored for anextended period of time after synthesis. By extended periods of time ismeant a period of greater than 24 hours, preferably greater than 36hours, more preferably greater than 48 hours, and most preferablygreater than 72 hours. In another embodiment, an agedmetalloaluminophosphate molecular sieve is a metalloaluminophosphatemolecular sieve that has been used in a catalytic process and has beenremoved from that process or temporarily retained under non-optimumprocess conditions such as in a shutdown phase. The period of ageing maybe under ambient conditions or elevated temperature, it may beundertaken under an inert atmosphere or a vacuum, for example in asealed container such as storage drum or metalloaluminophosphatemolecular sieve holding facility after manufacture of the sieve or acatalyst composition containing the metalloaluminophosphate molecularsieve. In the context of the present invention agedmetalloaluminophosphates are typically present in large amounts i.e. thebulk state. By bulk state is meant in the form of a large batch ofmaterial or catalyst comprising the metalloaluminophosphate. Typically abulk sample has a batch size of greater than 1 kilogram, preferablygreater than 10 kilogram and most preferably greater than 50 kilogram.The ageing may be undertaken in the presence of an inert gas in additionto the chemisorbed ammonia. In the present invention it is possible toutilize grades of inert gases which were hitherto unacceptable formetalloaluminophosphate molecular sieve storage due to inter alia theirmoisture content. Such gases may be of lower purity and quality e.g.they may contain higher than normal levels of impurities such as oxygenand/or moisture.

Metalloaluminophosphate Acidity and Infrared

Metalloaluminophosphate molecular sieve materials such assilicoaluminophosphate molecular sieves comprise a three-dimensionalmicroporous crystal framework structure and exhibit a particularlydesirable Broensted acid OH group spectrum in the Infrared, when thetemplate material has been properly removed. Broensted acid OH groupscan be conveniently characterized by Diffused Reflectance Infrared(DRIFTS) spectroscopy. The groups can be found throughout a range of4000 cm⁻¹ to 3400 cm⁻¹ of the IR spectrum. However,silicoaluminophosphate molecular sieves which exhibit desirablecatalytic activity upon appropriate template removal have Broensted acidOH groups having one or more bands in the IR with wave numbers rangingfrom about 3630 cm⁻¹ to about 3580 cm⁻¹, with non-Broensted OH groupslike Al—OH, P—OH and/or Si—OH being largely located in the range ofabout 4000 cm⁻¹ to about 3630 cm⁻¹. The non-Broensted OH groups are alsotypically located on the external surface of the molecular sieve or atregions within the sieve that exhibit internal defects.

In order to preserve catalytic activity, i.e., maintain acid catalystsites, this invention provides a method, which comprises chemisorbingammonia with the Broensted acid sites. The chemisorption may be observedand monitored through the use of DRIFTS. When the ammonia is chemisorbedthe infrared absorption bands relating to the Broensted acid sitesdecrease in intensity and are replaced by a new series of a infraredabsorption bands at lower wave numbers between 2300 cm⁻¹ and 3500 cm⁻¹,when ammonia is fully chemisorbed. When the chemisorbed ammonia issubsequently removed through desorption these characteristic infraredabsorptions decrease in intensity and eventually disappear whilst theoriginal Broensted acid absorption bands re-appear at higher wavenumbers. The intensity of the restored Broensted acidity infrared bandsis comparable to the bands observed prior to ammonia chemisorption. Thisinfrared behaviour is typical with the process of the present inventionand is a good method for determining that the acid sites and especiallythe Broensted acid sites of the molecular sieve have been protectedthrough chemisorption of ammonia and restored through desorption of theammonia.

Extended exposure of metalloaluminophosphate molecular sieves to ambientatmosphere results in a loss of catalytic activity. One suitable methodfor determining this activity and its loss is to determine the methanoladsorption capacity (MAC) of the molecular sieve after synthesis andactivation and to monitor this capacity with time after a period ofstorage. Ideally the MAC should remain as high as possible up to thepoint at which the molecular sieve is used in a conversion process suchas a methanol-to-olefins process. For molecular sieve catalysts whichare activated in situ, i.e. the template is removed on introduction ofthe molecular sieve to the conversion process, the time betweenactivation and actual contact with feed is short enough such that theinitial methanol adsorption capacity is essentially equivalent to themethanol adsorption capacity at feed contact. During conventionalstorage conditions e.g. under an inert atmosphere, this is not normallyachieved as the catalyst is progressively degraded by attack frommoisture. In the present invention the chemisorbed ammonia is effectivein retaining the methanol uptake properties of the molecular sieve,which are higher than those, achieved without ammonia chemisorption. Themeasurement of MAC may be used in the context of the present inventionto demonstrate the effective stabilization due to the chemisorption ofammonia. The use of ammonia chemisorption results in improved MAC valuesafter storage. According to this invention, it is preferred that the MACafter ammonia desorption is at least 15% of the original MAC prior tochemisorption of ammonia, preferably at least 40%, more preferably atleast 60%, and most preferably at least 80%. Techniques for measuringmethanol adsorption capacity are known to those of ordinary skill in theart.

Molecular Sieves and Catalysts Thereof

The metalloaluminophosphate molecular sieves which may be used in thepresent invention have been described in detail in numerous publicationsincluding for example, U.S. Pat. No. 4,567,029 (MeAPO where Me is Mg,Mn, Zn, or Co), U.S. Pat. No. 4,440,871 (SAPO), European PatentApplication EP-A-0 159 624 (ELAPSO where El is As, Be, B, Cr, Co, Ga,Ge, Fe, Li, Mg, Mn, Ti or Zn), U.S. Pat. No. 4,554,143 (FeAPO), U.S.Pat. Nos. 4,822,478, 4,683,217, 4,744,885 (FeAPSO), EP-A-0 158 975 andU.S. Pat. No. 4,935,216 (ZnAPSO, EP-A-0 161 489 (CoAPSO), EP-A-0 158 976(ELAPO, where EL is Co, Fe, Mg, Mn, Ti or Zn), U.S. Pat. No. 4,310,440(AlPO₄), EP-A-0 158 350 (SENAPSO), U.S. Pat. No. 4,973,460 (LiAPSO),U.S. Pat. No. 4,789,535 (LiAPO), U.S. Pat. No. 4,992,250 (GeAPSO), U.S.Pat. No. 4,888,167 (GeAPO), U.S. Pat. No. 5,057,295 (BAPSO), U.S. Pat.No. 4,738,837 (CrAPSO), U.S. Pat. Nos. 4,759,919, and 4,851,106 (CrAPO),U.S. Pat. Nos. 4,758,419, 4,882,038, 5,434,326 and 5,478,787 (MgAPSO),U.S. Pat. No. 4,554,143 (FeAPO), U.S. Pat. No. 4,894,213 (AsAPSO), U.S.Pat. No. 4,913,888 (AsAPO), U.S. Pat. Nos. 4,686,092, 4,846,956 and4,793,833 (MnAPSO), U.S. Pat. Nos. 5,345,011 and 6,156,931 (MnAPO), U.S.Pat. No. 4,737,353 (BeAPSO), U.S. Pat. No. 4,940,570 (BeAPO), U.S. Pat.Nos. 4,801,309, 4,684,617 and 4,880,520 (TiAPSO), U.S. Pat. Nos.4,500,651, 4,551,236 and 4,605,492 (TiAPO), U.S. Pat. Nos. 4,824,554,4,744,970 (CoAPSO), U.S. Pat. No. 4,735,806 (GaAPSO) EP-A-0 293 937(QAPSO, where Q is framework oxide unit [QO₂]), as well as U.S. Pat.Nos. 4,567,029, 4,686,093, 4,781,814, 4,793,984, 4,801,364, 4,853,197,4,917,876, 4,952,384, 4,956,164, 4,956,165, 4,973,785, 5,241,093,5,493,066 and 5,675,050, all of which are herein fully incorporated byreference.

Other metalloaluminophosphate molecular sieves include those describedin EP-0 888 187 B1 (microporous crystalline metallophosphates, SAPO₄(UIO-6)), U.S. Pat. No. 6,004,898 (molecular sieve and an alkaline earthmetal), U.S. patent application Ser. No. 09/511,943 filed Feb. 24, 2000(integrated hydrocarbon co-catalyst), PCT WO 01/64340 published Sep. 7,2001 (thorium containing molecular sieve), and R. Szostak, Handbook ofMolecular Sieves, Van Nostrand Reinhold, New York, N.Y. (1992), whichare all herein fully incorporated by reference.

The most preferred molecular sieves are SAPO molecular sieves, and metalsubstituted SAPO molecular sieves. In one embodiment, the metal is analkali metal of Group IA of the Periodic Table of Elements, an alkalineearth metal of Group IIA of the Periodic Table of Elements, a rare earthmetal of Group IIIB, including the Lanthanides: lanthanum, cerium,praseodymium, neodymium, samarium, europium, gadolinium, terbium,dysprosium, holmium, erbium, thulium, ytterbium and lutetium; andscandium or yttrium of the Periodic Table of Elements, a transitionmetal of Groups IVB, VB, VIB, VIIB, VIIIB, and IB of the Periodic Tableof Elements, or mixtures of any of these metal species. In one preferredembodiment, the metal is selected from the group consisting of Co, Cr,Cu, Fe, Ga, Ge, Mg, Mn, Ni, Sn, Ti, Zn and Zr, and mixtures thereof.

The metalloaluminophosphate molecular sieve may be represented by theempirical formula, on an anhydrous basis:mR:(M_(x)Al_(y)P_(z))O₂wherein R represents at least one templating agent, preferably anorganic templating agent; m is the number of moles of R per mole of(M_(x)Al_(y)P_(z))O₂ and m has a value from 0 to 1, preferably 0 to 0.5,and most preferably from 0 to 0.3; x, y, and z represent the molefraction of Al, P and M as tetrahedral oxides, where M is a metalselected from one of Group IA, IIA, IB, IIIB, IVB, VB, VIB, VIIB, VIIIBand Lanthanide's of the Periodic Table of Elements, preferably M isselected from one of the group consisting of Co, Cr, Cu, Fe, Ga, Ge, Mg,Mn, Ni, Sn, Ti, Zn and Zr. In an embodiment, m is greater than or equalto 0.2, and x, y and z are greater than or equal to 0.01. In anotherembodiment, m is greater than 0.1 to about 1, x is greater than 0 toabout 0.25, y is in the range of from 0.4 to 0.5, and z is in the rangeof from 0.25 to 0.5, more preferably m is from 0.15 to 0.7, x is from0.01 to 0.2, y is from 0.4 to 0.5, and z is from 0.3 to 0.5.

Non-limiting examples of SAPO and ALPO molecular sieves of the inventioninclude one or a combination of SAPO-5, SAPO-8, SAPO-11, SAPO-16,SAPO-17, SAPO-18, SAPO-20, SAPO-31, SAPO-34, SAPO-35, SAPO-36, SAPO-37,SAPO-40, SAPO-41, SAPO-42, SAPO-44 (U.S. Pat. No. 6,162,415), SAPO-47,SAPO-56, ALPO-5, ALPO-11, ALPO-18, ALPO-31, ALPO-34, ALPO-36, ALPO-37,ALPO-46, and metal containing molecular sieves thereof. The morepreferred molecular sieves include one or a combination of SAPO-18,SAPO-34, SAPO-35, SAPO-44, SAPO-56, ALPO-18 and ALPO-34, even morepreferably one or a combination of SAPO-18, SAPO-34, ALPO-34 andALPO-18, and metal containing molecular sieves thereof, and mostpreferably one or a combination of SAPO-34 and ALPO-18, and metalcontaining molecular sieves thereof.

As used herein, the term mixture is synonymous with combination and isconsidered a composition of matter having two or more components invarying proportions, regardless of their physical state. In particular,it encompasses physical mixtures as well as intergrowths of at least twodifferent molecular sieve structures; such as for example thosedescribed in PCT Publication No. WO 98/15496 and co-pending U.S. Ser.No. 09/924016 filed Aug. 7, 2001. In an embodiment, the molecular sieveis an intergrowth material having two or more distinct phases ofcrystalline structures within one molecular sieve composition. Inanother embodiment, the molecular sieve comprises at least oneintergrown phase of AEI and CHA framework-types. For example, SAPO-18,ALPO-18 and RUW-18 have an AEI framework-type, and SAPO-34 has a CHAframework-type. In a further embodiment the molecular sieve comprises amixture of intergrown material and non-intergrown material.

The method of stabilization of the present invention may be utilizedwith metalloaluminophosphate molecular sieves which are particularlyunstable to moisture exposure e.g. morpholine templated SAPO-34 and mayalso be used to stabilize relatively moisture insensitive molecularsieves such as dual templated (DPA and TEAOH) SAPO-34 materials whichmay be significantly affected during extended periods of ageing or onexposure to steam.

Molecular Sieve Synthesis

Generally, metalloaluminophosphate molecular sieves are synthesized bythe hydrothermal crystallization of one or more of a source ofaluminium, a source of phosphorous, a source of silicon, a templatingagent, and a metal containing compound. Typically, a combination ofsources of silicon, aluminium and phosphorous, optionally with one ormore templating agents and/or one or more metal containing compounds areplaced in a sealed pressure vessel, optionally lined with an inertplastic such as polytetrafluoroethylene, and heated, under acrystallization pressure and temperature, until a crystalline materialis formed, and then recovered by filtration, centrifugation and/ordecanting.

In a typical synthesis of the molecular sieve, the phosphorous-,aluminium-, and/or silicon-containing components are mixed, preferablywhile stirring and/or agitation and/or seeding with a crystallinematerial, optionally with an alkali metal, in a solvent such as water,and one or more templating agents, to form a synthesis mixture that isthen heated under crystallization conditions of pressure and temperatureas described in U.S. Pat. Nos. 4,440,871, 4,861,743, 5,096,684, and5,126,308, which are all herein fully incorporated by reference.

The preferred templating agent or template is a tetraethylammoniumcompounds such as tetraethyl ammonium hydroxide (TEAOH), tetraethylammonium phosphate, tetraethyl ammonium fluoride, tetraethyl ammoniumbromide, tetraethyl ammonium chloride and tetraethyl ammonium acetate.The most preferred templating agent is tetraethyl ammonium hydroxide andsalts thereof, particularly when producing a silicoaluminophosphatemolecular sieve. In one embodiment, a combination of two or more of anyof the above templating agents is used in combination with one or moreof a silicon-, aluminium-, and phosphorous-source.

Other suitable metalloaluminophosphate molecular sieves for use in thepresent invention may be prepared as described in U.S. Pat. No.5,879,655 (controlling the ratio of the templating agent tophosphorous), U.S. Pat. No. 6,005,155 (use of a modifier without asalt), U.S. Pat. No. 5,475,182 (acid extraction), U.S. Pat. No.5,962,762 (treatment with transition metal), U.S. Pat. Nos. 5,925,586and 6,153,552 (phosphorous modified), U.S. Pat. No. 5,925,800 (monolithsupported), U.S. Pat. No. 5,932,512 (fluorine treated), U.S. Pat. No.6,046,373 (electromagnetic wave treated or modified), U.S. Pat. No.6,051,746 (polynuclear aromatic modifier), U.S. Pat. No. 6,225,254(heating template), PCT WO 01/36329 published May 25, 2001 (surfactantsynthesis), PCT WO 01/25151 published Apr. 12, 2001 (staged acidaddition), PCT WO 01/60746 published Aug. 23, 2001 (silicon oil), U.S.patent application Ser. No. 09/929,949 filed Aug. 15, 2001 (coolingmolecular sieve), U.S. patent application Ser. No. 09/615,526 filed Jul.13, 2000 (metal impregnation including copper), U.S. patent applicationNo. 09/672,469 filed Sep. 28, 2000 (conductive microfilter), and U.S.patent application Ser. No. 09/754,812 filed Jan. 4, 2001 (freeze dryingthe molecular sieve), which are all herein fully incorporated byreference.

In one preferred embodiment, when a templating agent is used in thesynthesis of a molecular sieve, it is preferred that the templatingagent is substantially, preferably completely, removed aftercrystallization by numerous well known techniques, for example, heattreatments such as calcination. Calcination involves contacting themolecular sieve containing the templating agent with a gas, preferablycontaining oxygen, at any desired concentration at an elevatedtemperature sufficient to either partially or completely decompose andoxidize the templatingagent.

In one embodiment, the molecular sieve has a Si/Al ratio less than 0.65,preferably less than 0.40, more preferably less than 0.32, and mostpreferably less than 0.20.

Method for Making Molecular Sieve Catalyst Compositions

Once the molecular sieve is synthesized the molecular sieve may then betreated to chemisorb ammonia and then formulated into a molecular sievecatalyst composition. Alternatively the metalloaluminophosphatemolecular sieve as synthesized with or without activation may beformulated into a catalyst composition prior to ammonia chemisorption.In either instance the metalloaluminophosphate molecular sieve may becombined with a binder and/or a matrix material to form a molecularsieve catalyst composition or a formulated molecular sieve catalystcomposition. This formulated molecular sieve catalyst composition isformed into useful shape and sized particles by well-known techniquessuch as spray drying, pelletizing, extrusion, and the like.

There are many different binders that are useful in forming themolecular sieve catalyst composition. Non-limiting examples of bindersthat are useful alone or in combination include various types ofhydrated alumina, silicas, and/or other inorganic oxide sol. Onepreferred alumina containing sol is aluminium chlorhydrol. The inorganicoxide sol acts like glue binding the synthesized molecular sieves andother materials such as the matrix together, particularly after thermaltreatment. Upon heating, the inorganic oxide sol, preferably having alow viscosity, is converted into an inorganic oxide matrix component.For example, an alumina sol will convert to an aluminium oxide matrixfollowing heat treatment.

Aluminium chlorhydrol, a hydroxylated aluminium based sol containing achloride counter ion, has the general formula ofAl_(m)O_(n)(OH)_(o)Cl_(p).x(H₂O) wherein m is 1 to 20, n is 1 to 8, o is5 to 40, p is 2 to 15, and x is 0 to 30. In one embodiment, the binderis Al₁₃O₄(OH)₂₄Cl₇.12(H₂O) as is described in G. M. Wolterman, et al.,Stud. Surf. Sci. and Catal., 76, pages 105-144 (1993), which is hereinincorporated by reference. In another embodiment, one or more bindersare combined with one or more other non-limiting examples of aluminamaterials such as aluminium oxyhydroxide, γ-alumina, boehmite, diaspore,and transitional aluminas such as α-alumina, β-alumina, γ-alumina,δ-alumina, ε-alumina, κ-alumina, and ρ-alumina, aluminium trihydroxide,such as gibbsite, bayerite, nordstrandite, doyelite, and mixturesthereof.

In another embodiment, the binders are alumina sols, predominantlycomprising aluminium oxide, optionally including some silicon. In yetanother embodiment, the binders are peptised alumina made by treatingalumina hydrates such as pseudobohemite, with an acid, preferably anacid that does not contain a halogen, to prepare sols or aluminium ionsolutions. Non-limiting examples of commercially available colloidalalumina sols include Nalco 8676 available from Nalco Chemical Co.,Naperville, Ill., and Nyacol available from The PQ Corporation, ValleyForge, Pa.

The metalloaluminophosphate molecular sieve with or without chemisorbedammonia, may be combined with one or more matrix material(s). Matrixmaterials are typically effective in reducing overall catalyst cost, actas thermal sinks assisting in shielding heat from the catalystcomposition for example during regeneration, densifying the catalystcomposition, increasing catalyst strength such as crush strength andattrition resistance, and to control the rate of conversion in aparticular process.

Non-limiting examples of matrix materials include one or more of: rareearth metals, metal oxides including titania, zirconia, magnesia,thoria, beryllia, quartz, silica or sols, and mixtures thereof, forexample silica-magnesia, silica-zirconia, silica-titania, silica-aluminaand silica-alumina-thoria. In an embodiment, matrix materials arenatural clays such as those from the families of montmorillonite andkaolin. These natural clays include sabbentonites and those kaolinsknown as, for example, Dixie, McNamee, Georgia and Florida clays.Non-limiting examples of other matrix materials include: haloysite,kaolinite, dickite, nacrite, or anauxite. In one embodiment, the matrixmaterial, preferably any of the clays, are subjected to well knownmodification processes such as calcination and/or acid treatment and/orchemical treatment.

In one preferred embodiment, the matrix material is a clay or aclay-type composition, preferably the clay or clay-type compositionhaving a low iron or titania content, and most preferably the matrixmaterial is kaolin. Kaolin has been found to form a pumpable, high solidcontent slurry; it has a low fresh surface area, and it packs togethereasily due to its platelet structure. A preferred average particle sizeof the matrix material, most preferably kaolin, is from about 0.1 μm toabout 0.6 μm with a D90 particle size distribution of less than about 1μm.

In one embodiment, the binder, the molecular sieve with or withoutchemisorbed ammonia and the matrix material are combined in the presenceof a liquid to form a molecular sieve catalyst composition, where theamount of binder is from about 2% by weight to about 30% by weight,preferably from about 5% by weight to about 20% by weight, and morepreferably from about 7% by weight to about 15% by weight, based on thetotal weight of the binder, the molecular sieve and matrix material,excluding the liquid (after calcination).

In another embodiment, the weight ratio of the binder to the matrixmaterial used in the formation of the molecular sieve catalystcomposition is from 0:1 to 1:15, preferably 1:15 to 1:5, more preferably1:10 to 1:4, and most preferably 1:6 to 1:5. It has been found that ahigher sieve content, lower matrix content, increases the molecularsieve catalyst composition performance, however, lower sieve content,higher matrix material, improves the attrition resistance of thecomposition.

Upon combining the molecular sieve with or without chemisorbed ammonia,and the matrix material, optionally with a binder, in a liquid to form aslurry, mixing, preferably rigorous mixing is needed to produce asubstantially homogeneous mixture containing the molecular sieve.Non-limiting examples of suitable liquids include one or a combinationof water, alcohol, ketones, aldehydes, and/or esters. The most preferredliquid is water. In one embodiment, the slurry is colloid-milled for aperiod of time sufficient to produce the desired slurry texture,sub-particle size, and/or sub-particle size distribution. In the presentinvention the use of a metalloaluminophosphate molecular sieve, whichcomprises chemisorbed ammonia, is beneficial in the catalyst formulationprocess as the chemisorbed ammonia protects the molecular sieve from thedetrimental effects of the water utilized in the formulation process.

The molecular sieve with and without chemisorbed ammonia and matrixmaterial, and the optional binder, may be in the same or differentliquid, and may be combined in any order, together, simultaneously,sequentially, or a combination thereof. In the preferred embodiment, thesame liquid, preferably water is used. The molecular sieve, matrixmaterial, and optional binder, are combined in a liquid as solids,substantially dry or in a dried form, or as slurries, together orseparately. If solids are added together as dry or substantially driedsolids, it is preferable to add a limited and/or controlled amount ofliquid.

In one embodiment, the slurry of the molecular sieve with or withoutchemisorbed ammonia, binder and matrix materials is mixed or milled toachieve a sufficiently uniform slurry of sub-particles of the molecularsieve catalyst composition that is then fed to a forming unit thatproduces the molecular sieve catalyst composition. In a preferredembodiment, the forming unit is spray dryer. Typically, the forming unitis maintained at a temperature sufficient to remove most of the liquidfrom the slurry, and from the resulting molecular sieve catalystcomposition. The resulting catalyst composition when formed in this waytakes the form of microspheres. If chemisorbed ammonia is present priorto spray drying it may if desired be removed during the spray dryingprocess by selecting appropriate temperatures to ensure that the ammoniais desorbed. Alternatively the spray drying conditions may be selectedto ensure that the chemisorbed ammonia is substantially retained withinthe spray-dried material.

When a spray-drier is used as the forming unit, typically, the slurry ofthe molecular sieve and matrix material, and optionally a binder, isco-fed to the spray drying volume with a drying gas with an averageinlet temperature ranging from 200 C. to 550 C., and a combined outlettemperature ranging from 100 C. to about 225 C. In an embodiment, theaverage diameter of the spray dried formed catalyst composition is fromabout 40 μm to about 300 μm, preferably from about 50 μm to about 250μm, more preferably from about 50 μm to about 200 μm, and mostpreferably from about 65 μm to about 90 μm. If desired the average inletand/or outlet temperature of the spray drier may be selected to enablethe desorption of chemisorbed ammonia to occur during the spray dryingprocess.

During spray drying, the slurry is passed through a nozzle distributingthe slurry into small droplets, resembling an aerosol spray into adrying chamber. Atomization is achieved by forcing the slurry through asingle nozzle or multiple nozzles with a pressure drop in the range offrom 100 psia to 1000 psia (690 kPaa to 6895 kpaa). In anotherembodiment, the slurry is co-fed through a single nozzle or multiplenozzles along with an atomisation fluid such as air, steam, flue gas, orany other suitable gas.

In yet another embodiment, the slurry described above is directed to theperimeter of a spinning wheel that distributes the slurry into smalldroplets, the size of which is controlled by many factors includingslurry viscosity, surface tension, flow rate, pressure, and temperatureof the slurry, the shape and dimension of the nozzle(s), or the spinningrate of the wheel. These droplets are then dried in a co-current orcounter-current flow of air passing through a spray drier to form asubstantially dried or dried molecular sieve catalyst composition, morespecifically a molecular sieve in powder form.

Generally, the size of the powder is controlled to some extent by thesolids content of the slurry. However, control of the size of thecatalyst composition and its spherical characteristics are controllableby varying the slurry feed properties and conditions of atomisation.

Other methods for forming a molecular sieve catalyst composition isdescribed in U.S. patent application Ser. No. 09/617,714 filed Jul. 17,2000 (spray drying using a recycled molecular sieve catalystcomposition), which is herein incorporated by reference.

In another embodiment, the formulated molecular sieve catalystcomposition contains from about 1% to about 99%, more preferably fromabout 5% to about 90%, and most preferably from about 10% to about 80%,by weight of the molecular sieve based on the total weight of themolecular sieve catalyst composition.

In another embodiment, the weight percent of binder in or on the spraydried molecular sieve catalyst composition based on the total weight ofthe binder, molecular sieve, and matrix material is from about 2% byweight to about 30% by weight, preferably from about 5% by weight toabout 20% by weight, and more preferably from about 7% by weight toabout 15% by weight.

Once the molecular sieve catalyst composition is formed in asubstantially dry or dried state, to further harden and/or activate theformed catalyst composition, a heat treatment such as calcination, at anelevated temperature is usually performed. A conventional calcinationenvironment is air that typically includes a small amount of watervapour. Typical calcination temperatures are in the range from about400° C. to about 1,000° C., preferably from about 500° C. to about 800°C., and most preferably from about 550° C. to about 700° C., preferablyin a calcination environment such as air, nitrogen, helium, flue gas(combustion product lean in oxygen), or any combination thereof. Duringthis calcination process chemisorbed ammonia if present may be removedby desorption from the metalloaluminophosphate.

In one embodiment, calcination of the formulated molecular sievecatalyst composition is carried out in any number of well known devicesincluding rotary calciners, fluid bed calciners, batch ovens, and thelike. Calcination time is typically dependent on the degree of hardeningof the molecular sieve catalyst composition and the temperature.

In a preferred embodiment, the molecular sieve catalyst composition isheated in nitrogen at a temperature of from about 600° C. to about 700C. Heating is carried out for a period of time typically from 30 minutesto 15 hours, preferably from 1 hour to about 10 hours, more preferablyfrom about 1 hour to about 5 hours, and most preferably from about 2hours to about 4 hours.

Other methods for activating a molecular sieve catalyst composition aredescribed in, for example, U.S. Pat. No. 5,185,310 (heating molecularsieve of gel alumina and water to 450 C), PCT WO 00/75072 published Dec.14, 2000 (heating to leave an amount of template), and U.S. applicationSer. No. 09/558,774 filed Apr. 26, 2000 (rejuvenation of molecularsieve), which are all herein fully incorporated by reference

In addition to the metalloaluminophosphate molecular sieve, the catalystcompositions of the present invention may comprise one or several othercatalytically active materials. The present invention encompassestreating with ammonia catalyst compositions comprising one or severalmetalloaluminophosphate molecular sieve and another catalytically activematerial. In one embodiment, one or several metalloaluminophosphatemolecular sieves are combined with one more of the followingnon-limiting examples of catalytically active molecular sieves describedin the following: Beta (U.S. Pat. No. 3,308,069), ZSM-5 (U.S. Pat. Nos.3,702,886, 4,797,267 and 5,783,321), ZSM-11 (U.S. Pat. No. 3,709,979),ZSM-12 (U.S. Pat. No. 3,832,449), ZSM-12 and ZSM-38 (U.S. Pat. No.3,948,758), ZSM-22 (U.S. Pat. No. 5,336,478), ZSM-23 (U.S. Pat. No.4,076,842), ZSM-34 (U.S. Pat. No. 4,086,186), ZSM-35 (U.S. Pat. No.4,016,245, ZSM-48 (U.S. Pat. No. 4,397,827), ZSM-58 (U.S. Pat. No.4,698,217), MCM-1 (U.S. Pat. No. 4,639,358), MCM-2 (U.S. Pat. No.4,673,559), MCM-3 (U.S. Pat. No. 4,632,811), MCM-4 (U.S. Pat. No.4,664,897), MCM-5 (U.S. Pat. No. 4,639,357), MCM-9 (U.S. Pat. No.4,880,611), MCM-10 (U.S. Pat. No. 4,623,527), MCM-14 (U.S. Pat. No.4,619,818), MCM-22 (U.S. Pat. No. 4,954,325) MCM-41 (U.S. Pat. No.5,098,684), M-41S (U.S. Pat. No. 5,102,643), MCM-48 (U.S. Pat. No.5,198,203), MCM-49 (U.S. Pat. No. 5,236,575), MCM-56 (U.S. Pat. No.5,362,697), ALPO-11 (U.S. Pat. No. 4,310,440), titanium aluminosilicates(TASO), TASO-45 (EP-A-0 229,-295), boron silicates (U.S. Pat. No.4,254,297), titanium aluminophosphates (TAPO) (U.S. Pat. No. 4,500,651),mixtures of ZSM-5 and ZSM-11 (U.S. Pat. No. 4,229,424), ECR-18 (U.S.Pat. No. 5,278,345).

In another embodiment, the metalloaluminophosphate may be bound toanother molecular sieve, as disclosed for example in the following:SAPO-34 bound ALPO-5 (U.S. Pat. No. 5,972,203), PCT WO 98/57743published Dec. 23, 1988 (molecular sieve and Fischer-Tropsch), U.S. Pat.No. 6,300,535 (MFI-bound zeolites), and mesoporous molecular sieves(U.S. Pat. Nos. 6,284,696, 5,098,684, 5,102,643 and 5,108,725), whichare all herein fully incorporated by reference. Binder may no longer benecessary in such systems.

In a further embodiment, the metalloaluminophosphate molecular sieve maybe combined with a metal catalyst, for example as a Fischer-Tropschcatalyst.

Process for Using the Molecular Sieve Catalyst Compositions

The molecular sieve catalysts and compositions of the present inventionwith chemisorbed ammonia or after desorption of chemisorbed ammonia areuseful in a variety of processes including: cracking, hydrocracking,isomerization, polymerisation, reforming, hydrogenation,dehydrogenation, dewaxing, hydrodewaxing, absorption, alkylation,transalkylation, dealkylation, hydrodecylization, disproportionation,oligomerization, dehydrocyclization and combinations thereof.

The preferred processes of the present invention include a processdirected to the conversion of a feedstock comprising one or moreoxygenates to one or more olefin(s) and a process directed to theconversion of ammonia and one or more oxygenates to alkyl amines and inparticular methylamines.

In a preferred embodiment of the process of the invention, the feedstockcontains one or more oxygenates, more specifically, one or more organiccompound(s) containing at least one oxygen atom. In the most preferredembodiment of the process of invention, the oxygenate in the feedstockis one or more alcohol(s), preferably aliphatic alcohol(s) where thealiphatic moiety of the alcohol(s) has from 1 to 20 carbon atoms,preferably from 1 to 10 carbon atoms, and most preferably from 1 to 4carbon atoms. The alcohols useful as feedstock in the process of theinvention include lower straight and branched chain aliphatic alcoholsand their unsaturated counterparts.

Non-limiting examples of oxygenates include methanol, ethanol,n-propanol, isopropanol, methyl ethyl ether, dimethyl ether, diethylether, di-isopropyl ether, formaldehyde, dimethyl carbonate, dimethylketone, acetic acid, and mixtures thereof.

In the most preferred embodiment, the feedstock is selected from one ormore of methanol, ethanol, dimethyl ether, diethyl ether or acombination thereof, more preferably methanol and dimethyl ether, andmost preferably methanol.

In the most preferred embodiment, the feedstock, preferably of one ormore oxygenates, is converted in the presence of a molecular sievecatalyst composition into olefin(s) having 2 to 6 carbons atoms,preferably 2 to 4 carbon atoms. Most preferably, the olefin(s), alone orcombination, are converted from a feedstock containing an oxygenate,preferably an alcohol, most preferably methanol, to the preferredolefin(s) ethylene and/or propylene.

The most preferred process is generally referred to as gas-to-olefins(GTO) or alternatively, methanol-to-olefins (MTO). In a MTO process,typically an oxygenated feedstock, most preferably a methanol containingfeedstock, is converted in the presence of a molecular sieve catalystcomposition into one or more olefin(s), preferably and predominantly,ethylene and/or propylene, often referred to as light olefin(s).

In one embodiment of the process for conversion of a feedstock,preferably a feedstock containing one or more oxygenates, the amount ofolefin(s) produced based on the total weight of hydrocarbon produced isgreater than 50 weight percent, preferably greater than 60 weightpercent, more preferably greater than 70 weight percent.

The feedstock, in one embodiment, contains one or more diluent(s),typically used to reduce the concentration of the feedstock, and aregenerally non-reactive to the feedstock or molecular sieve catalystcomposition. Non-limiting examples of diluents include helium, argon,nitrogen, carbon monoxide, carbon dioxide, water, essentiallynon-reactive paraffins (especially alkanes such as methane, ethane, andpropane), essentially non-reactive aromatic compounds, and mixturesthereof. The most preferred diluents are water and nitrogen, with waterbeing particularly preferred.

The diluent, water, is used either in a liquid or a vapour form, or acombination thereof. The diluent is either added directly to a feedstockentering into a reactor or added directly into a reactor, or added witha molecular sieve catalyst composition. In one embodiment, the amount ofdiluent in the feedstock is in the range of from about 1 to about 99mole percent based on the total number of moles of the feedstock anddiluent, preferably from about 1 to 80 mole percent, more preferablyfrom about 5 to about 50, most preferably from about 5 to about 25. Inone embodiment, other hydrocarbons are added to a feedstock eitherdirectly or indirectly, and include olefin(s), paraffin(s), aromatic(s)(see for example U.S. Pat. No. 4,677,242, addition of aromatics) ormixtures thereof, preferably propylene, butylene, pentylene, and otherhydrocarbons having 4 or more carbon atoms, or mixtures thereof.

The process for converting a feedstock, especially a feedstockcontaining one or more oxygenates, in the presence of a molecular sievecatalyst composition of the invention, is carried out in a reactionprocess in a reactor, where the process is a fixed bed process, afluidised bed process (includes a turbulent bed process), preferably acontinuous fluidised bed process, and most preferably a continuous highvelocity fluidised bed process.

The reaction processes can take place in a variety of catalytic reactorssuch as hybrid reactors that have a dense bed or fixed bed reactionzones and/or fast fluidised bed reaction zones coupled together,circulating fluidised bed reactors, riser reactors, and the like.Suitable conventional reactor types are described in for example U.S.Pat. No. 4,076,796, U.S. Pat. No. 6,287,522 (dual riser), andFluidization Engineering, D. Kunii and 0. Levenspiel, Robert E. KriegerPublishing Company, New York, N.Y. 1977, which are all herein fullyincorporated by reference.

The preferred reactor type are riser reactors generally described inRiser Reactor, Fluidization and Fluid-Particle Systems, pages 48 to 59,F. A. Zenz and D. F. Othmo, Reinhold Publishing Corporation, New York,1960, and U.S. Pat. No. 6,166,282 (fast-fluidised bed reactor), and U.S.patent application Ser. No. 09/564,613 filed May 4, 2000 (multiple riserreactor), which are all herein fully incorporated by reference.

In the preferred embodiment, a fluidised bed process or high velocityfluidised bed process includes a reactor system, a regeneration systemand a recovery system.

The reactor system preferably is a fluid bed reactor system having afirst reaction zone within one or more riser reactor(s) and a secondreaction zone within at least one disengaging vessel, preferablycomprising one or more cyclones. In one embodiment, the one or moreriser reactor(s) and disengaging vessel is contained within a singlereactor vessel. Fresh feedstock, preferably containing one or moreoxygenates, optionally with one or more diluent(s), is fed to the one ormore riser reactor(s) in which a molecular sieve catalyst composition orcoked version thereof is introduced. In one embodiment, the molecularsieve catalyst composition or coked version thereof is contacted with aliquid or gas, or combination thereof, prior to being introduced to theriser reactor(s), preferably the liquid is water or methanol, and thegas is an inert gas such as nitrogen.

In an embodiment, the amount of fresh feedstock fed separately orjointly with-a-vapour feedstock, to a reactor system is in the range offrom 0.1 weight percent to about 85 weight percent, preferably fromabout 1 weight percent to about 75 weight percent, more preferably fromabout 5 weight percent to about 65 weight percent based on the totalweight of the feedstock including any diluent contained therein. Theliquid and vapour feedstocks are preferably the same composition, orcontain varying proportions of the same or different feedstock with thesame or different diluent.

The feedstock entering the reactor system is preferably converted,partially or fully, in the first reactor zone into a gaseous effluentthat enters the disengaging vessel along with a coked molecular sievecatalyst composition. In the preferred embodiment, cyclone(s) within thedisengaging vessel are designed to separate the molecular sieve catalystcomposition, preferably a coked molecular sieve catalyst composition,from the gaseous effluent containing one or more olefin(s) within thedisengaging zone. Cyclones are preferred, however, gravity effectswithin the disengaging vessel will also separate the catalystcompositions from the gaseous effluent. Other methods for separating thecatalyst compositions from the gaseous effluent include the use ofplates, caps, elbows, and the like.

In one embodiment of the disengaging system, the disengaging systemincludes a disengaging vessel; typically a lower portion of thedisengaging vessel is a stripping zone. In the stripping zone the cokedmolecular sieve catalyst composition is contacted with a gas, preferablyone or a combination of steam, methane, carbon dioxide, carbon monoxide,hydrogen, or an inert gas such as argon, preferably steam, to recoveradsorbed hydrocarbons from the coked molecular sieve catalystcomposition that is then introduced to the regeneration system. Inanother embodiment, the stripping zone is in a separate vessel from thedisengaging vessel and the gas is passed at a gas hourly superficialvelocity (GHSV) of from 1 hr⁻¹ to about 20,000 hr⁻¹ based on the volumeof gas to volume of coked molecular sieve catalyst composition,preferably at an elevated temperature from 250° C. to about 750° C.,preferably from about 350° C. to 650° C., over the coked molecular sievecatalyst composition.

The conversion temperature employed in the conversion process,specifically within the reactor system, is in the range of from about200° C. to about 1000° C., preferably from about 250° C. to about 800°C., more preferably from about 250° C. to about 750 ° C., yet morepreferably from about 300° C. to about 650° C., yet even more preferablyfrom about 350° C. to about 600° C. most preferably from about 350° C.to about 550° C.

The conversion pressure employed in the conversion process, specificallywithin the reactor system, varies over a wide range including autogenouspressure. The conversion pressure is based on the partial pressure ofthe feedstock exclusive of any diluent therein. Typically the conversionpressure employed in the process is in the range of from about 0.1 kpaato about 5 MPaa, preferably from about 5 kPaa to about 1 MPaa, and mostpreferably from about 20 kpaa to about 500 kPaa.

The weight hourly space velocity (WHSV), particularly in a process forconverting a feedstock containing one or more oxygenates in the presenceof a molecular sieve catalyst composition within a reaction zone, isdefined as the total weight of the feedstock excluding any diluents tothe reaction zone per hour per weight of molecular sieve in themolecular sieve catalyst composition in the reaction zone. The WHSV ismaintained at a level sufficient to keep the catalyst composition in afluidised state within a reactor.

Typically, the WHSV ranges from about 1 hr⁻¹ to about 5000 h⁻¹,preferably from about 2 hr⁻¹ to about 3000 hr⁻¹, more preferably fromabout 5 hr⁻¹ to about 1500 hr⁻¹, and most preferably from about 10 hr⁻¹to about 1000 hr⁻¹. In one preferred embodiment, the WHSV is greaterthan 20 hr⁻¹; preferably the WHSV for conversion of a feedstockcontaining methanol and dimethyl ether is in the range of from about 20hr⁻¹ to about 300 hr⁻¹.

The superficial gas velocity (SGV) of the feedstock including diluentand reaction products within the reactor system is preferably sufficientto fluidise the molecular sieve catalyst composition within a reactionzone in the reactor. The SGV in the process, particularly within thereactor system, more particularly within the riser reactor(s), is atleast 0.1 meter per second (m/sec), preferably greater than 0.5 m/sec,more preferably greater than 1 m/sec, even more preferably greater than2 m/sec, yet even more preferably greater than 3 m/sec, and mostpreferably greater than 4 m/sec. See for example U.S. patent applicationSer. No. 09/708,753 filed Nov. 8, 2000, which is herein incorporated byreference.

In one preferred embodiment of the process for converting an oxygenateto olefin(s) using a silicoaluminophosphate molecular sieve catalystcomposition, the process is operated at a WHSV of at least 20 hr⁻¹ and aTemperature Corrected Normalized Methane Selectivity (TCNMS) of lessthan 0.016, preferably less than or equal to 0.01. See for example U.S.Pat. No. 5,952,538, which is herein fully incorporated by reference.

In another embodiment of the processes for converting an oxygenate suchas methanol to one or more olefin(s) using a molecular sieve catalystcomposition, the WHSV is from 0.01 hr⁻¹ to about 100 hr⁻¹, at atemperature of from about 350° C. to 550° C., and silica to Me₂O₃ (Me isa Group IIIA or VIII element from the Periodic Table of Elements) molarratio of from 300 to 2500. See for example EP-0 642 485 B1, which isherein fully incorporated by reference.

Other processes for converting an oxygenate such as methanol to one ormore olefin(s) using a molecular sieve catalyst composition aredescribed in PCT WO 01/23500 published Apr. 5, 2001 (propane reductionat an average catalyst feedstock exposure of at least 1.0), which isherein incorporated by reference.

The coked molecular sieve catalyst composition is withdrawn from thedisengaging vessel, preferably by one or more cyclones(s), andintroduced to the regeneration system. The regeneration system comprisesa regenerator where the coked catalyst composition is contacted with aregeneration medium, preferably a gas containing oxygen, under generalregeneration conditions of temperature, pressure and residence time.

Non-limiting examples of the regeneration medium include one or more ofoxygen, O₃, SO₃, N₂O, NO, NO₂, N₂O₅, air, air diluted with nitrogen orcarbon dioxide, oxygen and water (U.S. Pat. No. 6,245,703), carbonmonoxide and/or hydrogen. The regeneration conditions are those capableof burning coke from the coked catalyst composition, preferably to alevel less than 0.5 weight percent based on the total weight of thecoked molecular sieve catalyst composition entering the regenerationsystem. The coked molecular sieve catalyst composition withdrawn fromthe regenerator forms a regenerated molecular sieve catalystcomposition.

The regeneration temperature is in the range of from about 200° C. toabout 1500° C., preferably from about 300° C. to about 1000° C., morepreferably from about 450° C. to about 750° C., and most preferably fromabout 550° C. to 700° C. The regeneration pressure is in the range offrom about 15 psia (103 kpaa) to about 500 psia (3448 kPaa), preferablyfrom about 20 psia (138 kPaa) to about 250 psia (1724 kpaa), morepreferably from about 25 psia (172kPaa) to about 150 psia (1034 kpaa),and most preferably from about 30 psia (207 kPaa) to about 60 psia (414kPaa).

The preferred residence time of the molecular sieve catalyst compositionin the regenerator is in the range of from about one minute to severalhours, most preferably about one minute to 100 minutes, and thepreferred volume of oxygen in the gas is in the range of from about 0.01mole percent to about 5 mole percent based on the total volume of thegas.

In one embodiment, regeneration promoters, typically metal containingcompounds such as platinum, palladium and the like, are added to theregenerator directly, or indirectly, for example with the coked catalystcomposition. Also, in another embodiment, a fresh molecular sievecatalyst composition is added to the regenerator containing aregeneration medium of oxygen and water as described in U.S. Pat. No.6,245,703, which is herein fully incorporated by reference.

In an embodiment, a portion of the coked molecular sieve catalystcomposition from the regenerator is returned directly to the one or moreriser reactor(s), or indirectly, by pre-contacting with the feedstock,or contacting with fresh molecular sieve catalyst composition, orcontacting with a regenerated molecular sieve catalyst composition or acooled regenerated molecular sieve catalyst composition described below.

The burning of coke is an exothermic reaction, and in an embodiment, thetemperature within the regeneration system is controlled by varioustechniques in the art including feeding a cooled gas to the regeneratorvessel, operated either in a batch, continuous, or semi-continuous mode,or a combination thereof. A preferred technique involves withdrawing theregenerated molecular sieve catalyst composition from the regenerationsystem and passing the regenerated molecular sieve catalyst compositionthrough a catalyst cooler that forms a cooled regenerated molecularsieve catalyst composition. The catalyst cooler, in an embodiment, is aheat exchanger that is located either internal or external to theregeneration system.

In one embodiment, the cooler regenerated molecular sieve catalystcomposition is returned to the regenerator in a continuous cycle,alternatively, (see U.S. patent application Ser. No. 09/587,766 filedJun. 6, 2000) a portion of the cooled regenerated molecular sievecatalyst composition is returned to the regenerator vessel in acontinuous cycle, and another portion of the cooled molecular sieveregenerated molecular sieve catalyst composition is returned to theriser reactor(s), directly or indirectly, or a portion of theregenerated molecular sieve catalyst composition or cooled regeneratedmolecular sieve catalyst composition is contacted with by-productswithin the gaseous effluent (PCT WO 00/49106 published Aug. 24, 2000),which are all herein fully incorporated by reference. In anotherembodiment, a regenerated molecular sieve catalyst composition contactedwith an alcohol, preferably ethanol, 1-propnaol, 1-butanol or mixturethereof, is introduced to the reactor system, as described in U.S.patent application Ser. No. 09/785,122 filed Feb. 16, 2001, which isherein fully incorporated by reference.

Other methods for operating a regeneration system are in disclosed U.S.Pat. No. 6,290,916 (controlling moisture), which is herein fullyincorporated by reference.

The regenerated molecular sieve catalyst composition withdrawn from theregeneration system, preferably from the catalyst cooler, is combinedwith a fresh molecular sieve catalyst composition and/or re-circulatedmolecular sieve catalyst composition and/or feedstock and/or fresh gasor liquids, and returned to the riser reactor(s). In another embodiment,the regenerated molecular sieve catalyst composition withdrawn from theregeneration system is returned to the riser reactor(s) directly,preferably after passing through a catalyst cooler. In one embodiment, acarrier, such as an inert gas, feedstock vapour, steam or the like,semi-continuously or continuously, facilitates the introduction of theregenerated molecular sieve catalyst composition to the reactor system,preferably to the one or more riser reactor(s).

By controlling the flow of the regenerated molecular sieve catalystcomposition or cooled regenerated molecular sieve catalyst compositionfrom the regeneration system to the reactor system, the optimum level ofcoke on the molecular sieve catalyst composition entering the reactor ismaintained. There are many techniques for controlling the flow of amolecular sieve catalyst composition described in Michael Louge,Experimental Techniques, Circulating Fluidised Beds, Grace, Avidan andKnowlton, eds. Blackie, 1997 (336-337), which is herein incorporated byreference.

Coke levels on the molecular sieve catalyst composition are measured bywithdrawing from the conversion process the molecular sieve catalystcomposition at a point in the process and determining its carboncontent. Typical levels of coke on the molecular sieve catalystcomposition, after regeneration is in the range of from 0.01 weightpercent to about 15 weight percent, preferably from about 0.1 weightpercent to about 10 weight percent, more preferably from about 0.2weight percent to about 5 weight percent, and most preferably from about0.3 weight percent to about 2 weight percent based on the total weightof the molecular sieve and not the total weight of the molecular sievecatalyst composition.

In one preferred embodiment, the mixture of fresh molecular sievecatalyst composition and regenerated molecular sieve catalystcomposition and/or cooled regenerated molecular sieve catalystcomposition contains in the range of from about 1 to 50 weight percent,preferably from about 2 to 30 weight percent, more preferably from about2 to about 20 weight percent, and most preferably from about 2 to about10 coke or carbonaceous deposit based on the total weight of the mixtureof molecular sieve catalyst compositions. See for example U.S. Pat. No.6,023,005, which is herein fully incorporated by reference.

The gaseous effluent is withdrawn from the disengaging system and ispassed through a recovery system. There are many well-known recoverysystems, techniques and sequences that are useful in separatingolefin(s) and purifying olefin(s) from the gaseous effluent. Recoverysystems generally comprise one or more or a combination of a variousseparation, fractionation and/or distillation towers, columns,splitters, or trains, reaction systems such as ethylbenzene manufacture(U.S. Pat. No. 5,476,978) and other derivative processes such asaldehydes, ketones and ester manufacture (U.S. Pat. No. 5,675,041), andother associated equipment for example various condensers, heatexchangers, refrigeration systems or chill trains, compressors,knock-out drums or pots, pumps, and the like.

The metalloaluminophosphate molecular sieve materials and catalystcompositions of the present invention may be used in the manufacture ofalkylamines, using ammonia. Examples of suitable processes are asdescribed in published European Patent Application EP 0 993 867 A1, andin U.S. Pat. No. 6,153,798 to Hidaka et.al, which are herein fullyincorporated by reference.

In order to provide a better understanding of the present inventionincluding representative advantages thereof, the following examples areoffered.

EXAMPLES Methods

Dynamic Gas-Volumetric Adsorption Apparatus

The apparatus used for treatment with ammonia was a dynamicgas-volumetric adsorption apparatus as illustrated in FIG. 1.

Briefly, the apparatus consists of two calibrated volumes, the ‘deadvolume’ and the ‘sample container’. The dead volume consists of aHg-manometer (A), a fixed-step gas burette (B), a circulation pump (C)and a cold trap (D). The dead volume is separated from the samplecontainer (E) by two valves and by shutting the interconnecting valve itis possible to enforce a unidirectional flow through the samplecontainer. Both volumes are connected to a high vacuum system (rotationpump+diffusion pump), which allows a pressure reduction to <<0.1 Pa. Theapparatus is constructed to maintain this vacuum for several days.Calcined SAPO-34 samples were degassed in sample container (E) overnightin vacuum at 300° C. and then NH₃ was contacted in situ with the SAPO-34at different temperatures. The chemisorption was completed when it wasdetermined through observation of the pressure drop on the Hg-manometerthat the pressure has reached a steady value. This occurred afterapproximately 30 mins using elevated temperatures. When the sample wastreated at 20° C. it was necessary due to the volume limitations on theadsorption apparatus to undertake multiple injections and exposures tothe ammonia gas; under these conditions chemisorption was completed whena pressure increase was observed indicating that no further ammoniacould be chemisorbed onto the sample.

TGA-DTG

TGA measurements were recorded on a Mettler TG 50/TA 3000 thermobalance,controlled by a TClOA microprocessor. The TGA diagrams were recordedunder a nitrogen flow (200 mL/min) at a heating rate of 5° C./min.

XRD

X-ray Diffractograms were recorded on a Philips PW 1840 powderdiffractometer, using Ni-filtered Cu Kα radiation (X=0.154 nm).

N₂—Adsorption and Desorption

Porosity and surface area studies were performed on a QuantachromeAutosorb-1-MP automated gas adsorption system. All samples were outgassed for 16 h at 200° C. prior to adsorption. Gas adsorption occurredusing nitrogen as the adsorbate at liquid nitrogen temperature (77° K).Micropore volumes were determined using the t-plot method of De Boer, inwhich the amount of N₂ adsorbed is replotted against t. This parameterstands for the multilayer thickness for the adsorption of N₂ on anon-porous reference solid.

Methanol Adsorption Capacity

The methanol adsorption capacity is measured in a gravimetric adsorptionapparatus, which comprised a quartz spring. After degassing the SAPO-34in vacuum at 200° C., the sample was cooled to room temperature andmethanol vapour was allowed into the system at room temperature. Bymeasuring the weight changes at regular time intervals, not only theadsorption capacity but also the adsorption kinetics was measured. Themethanol adsorption capacity (MAC) is the amount of methanol adsorbedwhen the system is in equilibrium and is given as the increase in weight(in %) of a dehydrated SAPO-34 after methanol uptake.

Methanol Conversion During MTO

The MTO reaction (Methanol-to-Olefins) was performed in a stainlesssteel, fixed bed continuous reactor. 100% methanol is added as feed. Thereaction is carried out at 450° C., a reactor pressure of 15 psig and aWHSV of 26 g/g.hr. Reaction products were analyzed with an on-line GC.Methanol conversion is calculated as 100−(wt. % methanol+wt. % DME) leftin the product.

Infrared Spectroscopy

DRIFTS (Diffuse Reflectance Infrared Fourier Transformed Spectroscopy)spectra were recorded on a Nicolet Nexus FTIR spectrometer equipped withan in situ DRIFTS cell (Spectra Tech) and an MCT detector. The SAPO-34was mixed with KBr (95% KBr; 5% SAPO-34), the measurements wereperformed in vacuum at 200° C. or 4000 C. after degassing the SAPO-34 insitu for 15 minutes. The spectral resolution was 4 cm⁻¹. Pure KBr wasrun as a reference.

Example 1

Preparation of SAPO-34

SAPO-34 was crystallized in the presence of morpholine (R) as templatingagent. A mixture of the following mole ratio composition was prepared:0.6 SiO₂/Al₂O₃/P₂O₅/3R/50 H₂O

80.1 g of Condea Pural SB was mixed with 422.0 g of deionised water, toform a slurry. To this slurry was added 135.6 g of phosphoric acid(85%). These additions were made with stirring to form a homogeneousmixture. To this homogeneous mixture 53.2 g of Ludox AS40 was added,followed by the addition of 157.2 g of morpholine (R) with mixing toform a homogeneous mixture. To this homogeneous mixture was added 1.97 gof a seeding slurry containing 8.68 wt % zeolite chabasite crystals.

This homogeneous mixture was crystallized without agitation in a 1 literstainless steel autoclave. The mixture was heated to 175° C. in 6 hoursand kept at this temperature for 48 hours. This provided a slurry ofcrystalline molecular sieve. The slurry was evenly divided over 2 oneliter bottles and the crystals were separated from the mother liquor bycentrifuging. The solids in each bottle were further washed 4 times with850 ml of deionised water. The conductivity of the last-wash water was˜40 μS/cm. The solids were dried overnight at 120° C. 15.2% crystals byweight of the initial synthesis mixture were obtained.

Example 2

Treatment and Ageing of SAPO-34 with NH₃

Anhydrous ammonia (grade 3.6) was supplied as a liquefied gas fromPraxair, Potassium nitrate, p.a. was supplied from Acros organics.

The SAPO-34 was activated (calcined) prior to the modification.Calcination was performed muffle furnace at 625° C. for 4 hours underambient air (heating rate: 5 ° C./min). The calcined SAPO-34 wastransferred into a dynamic gas-volumetric adsorption apparatus anddegassed overnight in vacuum at 300° C. NH₃ was contacted in situ withthe SAPO-34 for 30 mins at different temperatures leading to differentammonia loadings. The degree of modification was measuredvolumetrically.

Ageing of the SAPO-34

The SAPO-34 with and without ammonia chemisorption was hydrated (aged)in a moisture-containing atmosphere (90% relative humidity) for periodsof time from less than 1 day up to 100 days. 90% relative humidity wasestablished by a saturated KNO3 solution in an exciccator.

Dehydration and Ammonia Desorption of Aged SAPO-34

After the ageing, the SAPO-34 samples were dehydrated in a mufflefurnace at 625° C. for 4 hours under ambient air (heating rate: 5°C./min) and at the same time any chemisorbed ammonia if present wasdesorbed, the samples were then characterized and tested.

TEST RESULTS

Methanol Adsorption Capacity

FIG. 2 shows the methanol adsorption capacity of SAPO-34 after differentNH₃-treatments as a function of the ageing time (♦ parent SAPO-34; ●SAPO-34 treated-with NH₃ at 20° C. prior to the ageing treatment; ▴SAPO-34 treated with NH₃ at 150° C. prior to the ageing treatment; and ▪SAPO-34 treated with NH₃ at 210° C. prior to the ageing treatment).

The methanol adsorption capacity is given as weight percent; this is theincrease in weight percent of the calcined SAPO-34 after methanoluptake. This data clearly shows that the untreated SAPO-34 looses itsmethanol adsorption capacity rapidly with ageing. The ammoniachemisorption treatment at 20° C. shows a significant improvement inmethanol adsorption capacity on ageing. The 150° C. and 210° C. treatedsamples show a marked improvement with maintenance of the SAPO-34stability after extended periods of time.

Effect of Ageing on Methanol Conversion

FIG. 3 shows the methanol conversion of SAPO-34 without ammoniachemisorption after various periods of ageing (▪ parent SAPO-34, notaged; ▴ SAPO-34, aged for 3 days; ♦ SAPO-34, aged for 7 days). FIG. 4shows the methanol conversion for ammonia chemisorbed SAPO-34 (treatedat 210° C.) after various periods of extended ageing (▪ parent SAPO34,not aged; ▴ SAPO-34, treated with NH₃, aged for 3 days; ♦ SAPO-34,treated with NH₃, aged for 6 days; ● SAPO-34, treated with NI-I₃, agedfor 7 days; X SAPO-34, treated with NH₃, aged for 100 days).

FIG. 3 clearly shows how ageing has a detrimental effect on the MTOperformance of a SAPO-34 catalyst, which looses all activity after onlyseven days ageing.

This is in contrast with the data shown in FIG. 4, which illustratesthat even after extensive ageing (>100 days) the NH₃, treated sampleretains catalytic activity.

Pore Volume Data Calculated From N₂—Adsorption Isotherm

The pore volume data is provided in the following table. Samplemicropore volume (mL/g) Parent SAPO-34, not aged 0.249 Parent SAPO-34,aged for 7 days 0.006 SAPO-34, treated with NH₃ at 210° C., aged 0.257for 7 days SAPO-34, treated with NH₃ at 20° C., aged 0.111 for 7 days

This data illustrates that the NH₃ treatment has a positive effect oncatalyst porosity on ageing. The treatment at 210° C. being particularlyeffective in maintaining porosity.

XRD Patterns of SAP-34 Samples

FIG. 5 illustrates the effect of ageing on the crystallinity of treatedand untreated SAPO-34 catalysts (a=Parent SAPO-34, not aged, b=ParentSAPO-34, 22 days aged, c=SAPO-34, treated with NH₃ at 20° C., 22 daysaged, and d=SAPO-34, treated with NH₃ at 210° C., 22 days aged). Thisfigure shows that without the NH₃ treatment there is a complete loss ofcrystalline structure after only 22 days ageing. However, with NH₃treatment the crystalline structure is retained on ageing.

IR Spectra

FIG. 6 illustrates the effect of ammonia chemisorption and desorption onan activated SAPO-34 molecular sieve. The figure shows that afterammonia chemisorption the Broensted acid band at approximately 3650 cm⁻¹is replaced by a series of new IR bands between 3500 cm⁻¹ and 2300 cm⁻¹.The figure also shows that these bands are retained during ageing of theammonia chemisorbed molecular sieve and that after desorption of ammoniafrom the aged molecular sieve the original Broensted acid band returnsindicating regeneration of the Broensted acid sites in the molecularsieve.

Example 3

Steam Ageing

SAPO-34 molecular sieves were prepared using the general procedureprovided in Example 1. In addition samples were also prepared using acombined templating agent of dipropylamine (DPA) and tetraethylammoniumhydroxide (TEAOH). The resultant SAPO-34 materials were activated bycalcination to remove substantially all the organic template and werechemisorbed with ammonia at 210° C. using the method described above.These materials are referred to as SAPO-34 (M) for the morpholinetemplated material and SAPO-34 (D) for the dual templated material.

Ammonia chemisorbed samples and untreated samples of these SAPO-34materials were exposed to steam in an SS Teflon lined autoclave, whichwas held at 110° C. under autogeneous pressure for up to 30 hours.

The samples before and after steaming were characterized using DRIFTS,XRD, methanol uptake and methanol conversion. The effectiveness of eachsample in methanol conversion was also evaluated where appropriate afterdesorption of the chemisorbed ammonia, using the general procedureprovided above.

SAPO-34 (M)

On steaming the untreated SAPO-34 showed almost complete loss of theBroensted acid infrared band after only 25 hours. However, the SAPO-34(M) sample which had been treated with ammonia retained the Broenstedacid infrared band after 25 hours of steaming; this band beingregenerated after desorption of the chemisorbed ammonia.

The XRD demonstrated that under steaming the untreated parent SAPO-34(M) experienced almost complete loss of crystallinity within 25 hours.This was contrasted with the SAPO-34 (M) samples treated with ammonia,which after ammonia desorption exhibited virtually no significant lossof crystallinity.

After steaming for 25 hours the untreated parent SAPO-34 (M) exhibited amethanol uptake index at 25 hours of only 0.11 whereas the ammoniachemisorbed SAPO-34 (M) sample exhibited a methanol uptake index of0.89.

These results demonstrate that the SAPO-34 (M) samples with chemisorbedammonia are remarkably resistant to hydrolytic attack by steam.

SAPO-34 (D)

The methanol conversion data for SAPO-34 (D) samples is provided in thefollowing table:

-   -   Sample 1=Untreated SAPO-34 (D) without steam ageing    -   Sample 2=Untreated SAPO-34 (D) with steam ageing for 25 hours at        110° C.

Sample 3=Ammonia chemisorbed SAPO-34 (D) with steam ageing for 25 hoursat 110° C. and after desorption of chemisorbed ammonia. IntegratedSelectivities Sam- Total Total ple CH₄ Ethylene Ethane Propylene PropaneC4+ Olefins 1 0.84 32.12 0.81 41.43 2.58 22.22 73.56 2 1.25 28.85 0.8038.89 6.13 24.08 67.75 3 1.10 31.84 0.93 40.40 4.37 21.36 72.22

This data illustrates that the steam ageing has a detrimental effect onthe olefins yield when an untreated SAPO-34 (D) is used as MTO catalyst;in addition steaming also results in an increased production of propanewhich is undesirable. Although the ammonia chemisorbed SAPO-34 (D) doesnot have the same performance as the untreated fresh parent SAPO-34 (D)it does perform significantly better than the untreated aged sample. Allof these SAPO-34 (D) samples showed virtually no loss of crystallinityon exposure to steam, which is in contrast to the effect of steam on themorpholine templated materials. In addition although the XRD dataindicates that there is no significant loss of crystallinity for Sample2 the methanol conversion data clearly demonstrates that this sample haslost a significant amount of catalytic activity on steam ageing.

While the present invention has been described and illustrated byreference to particular embodiments, those of ordinary skill in the artwill appreciate that the invention lends itself to variations notnecessarily illustrated herein. For example, it is also contemplated themolecular sieves described herein are useful as absorbents, adsorbents,gas separators, detergents, water purifiers, and other various uses suchas agriculture and horticulture.

1-65. (canceled)
 66. A hydrocarbon conversion process comprising the steps of: (a) introducing a feedstock to a reactor system in the presence of a metalloaluminophosphate molecular sieve having ammonia chemisorbed thereon; (b) withdrawing from the reactor system an effluent stream; and (c) passing the effluent gas through a recovery system recovering at least the one or more conversion products.
 67. The process of claim 66 wherein the feedstock comprises one or more oxygenates.
 68. The process of claim 67 wherein the one or more oxygenates comprises methanol.
 69. The process of claim 66 wherein the one or more conversion products comprises one or more olefins.
 70. The process of claim 69 wherein the one or more olefins comprises ethylene, propylene and mixtures thereof.
 71. The process of claim 70, wherein the metalloaluminophosphate molecular sieve is selected from the group consisting of SAPO-18, SAPO-34, SAPO-35, SAPO 44, SAPO-47, MCM-2, metal containing forms of each of the foregoing, and mixtures thereof.
 72. The process of claim 66 wherein the feedstock comprises one or more oxygenates and ammonia.
 73. The process of claim 72 wherein the one or more conversion products are comprises one or more alkylamines.
 74. The process of claim 73 wherein the one or more alkylamines comprises one or more methylamines.
 75. The process according to claim 74 wherein the one or more oxygenates comprises methanol. 